What if it’s Not Spinal Stenosis? Myofascial Pain Syndrome.

by LMatthews on July 30, 2012

What if it's not spinal stenosis? Consider myofascial pain as a differential diagnosis for back pain.

Back pain, referred pain, tenderness, popping, clicking, and stiffness can all lead to a diagnosis of spinal stenosis, especially when an MRI or X-ray reveals spinal narrowing. But what if it’s not spinal stenosis causing your symptoms? Many people have some degree of spinal narrowing as they age and not all are symptomatic, so is your chronic back pain and restricted movement due to myofascial pain syndrome rather than spinal stenosis?

What is Myofascial Pain?

Myofascial pain is a common and excruciating disorder that can affect the skeletal muscles across the body and, therefore, create a number of tender points and symptoms. Around half of the weight of our body is made up of skeletal muscle so it is easy to see how this condition can severely reduce quality of life, particularly if not diagnosed quickly and treated effectively. Almost everyone is thought to develop at least one trigger point during their lifetime and some 14.4% of the general population are thought to suffer from chronic musculoskeletal pain, with myofascial pain syndrome indicated in 21-93% of those with regional pain.

Spinal Stenosis Differential Diagnosis

Unfortunately, due to the disparate symptoms that can result from myofascial pain syndrome it may be some time before patients approach their physician for a diagnosis. Even then the process of getting diagnosed may be protracted as other conditions have to be considered as differential diagnoses such as spinal stenosis, fibromyalgia, and even depression. There is some overlap with fibromyalgia but myofascial pain is connected to specific trigger points whereas pain in fibromyalgia is widespread and due to heightened pain sensitivity rather than specific skeletal muscle involvement.

Myofascial Pain Symptoms

Classic symptoms of myofascial pain include restricted range of motion (ROM), and a local twitch response to local stimulation in the muscles affected. Muscle weakness may also occur, as with spinal stenosis, but the muscles do not tend to atrophy in cases of myofascial pain whereas muscles weakened by reduced innervation from pinched nerves in the spine will lose strength over time. Trigger points (TrPs) in myofascial pain syndrome are defined as primary and satellite locations and those satellite TrPs, causing pain in a limited but remote area, tend to become asymptomatic once the primary TrP has been treated. It may be that some residual stiffness and restricted mobility occurs, without pain, in latent trigger points.

Causes of Myofascial Pain

The cause of myofascial pain syndrome is multifactorial and is thought connected to stress on the muscles that occurs suddenly or in abnormal circumstances. This may be from discrepancies in leg-length (which can also cause spinal stenosis), as well as asymmetry in the growth of the skeleton or resulting from a surgical procedure or accident. Posture also plays a role in some cases of myofascial pain as symptoms can arise following prolonged adoption of a sedentary position. Various nutritional factors are also implicated in the condition such as anaemia, calcium insufficiency, low levels of potassium, iron, and vitamins C, B1, B6, and B12. Again, linking myofascial pain with fibromyalgia, it may be that sleep deprivation is also a trigger for the condition, as can be chronic infection and depression. Spinal stenosis itself may result in myofascial pain syndrome through radiculopathy and muscular stress.

Myofascial Pain Triggers

The same eighteen tender points used in diagnosing fibromyalgia are also active amongst the trigger points found in myofascial pain syndrome. One theory to explain the pathophysiology of myofascial pain involves the sensitization of the parts of the muscles (the end-plates) that receive and respond to signals from the spinal cord for movement. A lower trigger point for mechanic action can cause muscle fatigue, spasm, and pain. The more trigger points that are active the more intense spontaneous pain appears to be in the condition and it is thought that this hypersensitivity in the muscles may be connected to dysfunction in the spinal cord to some degree.

Diagnosing Myofascial Pain

Diagnosis of myofascial pain may include tests to detect lower skin resistance to electric current, which has been found to be associated with active trigger points compared to surrounding tissue. Patients may also be tested for illnesses which increase the likelihood of myofascial pain, such as an underactive thyroid, poor blood sugar control (hypoglycaemia), and deficiencies in various nutrients. Blood flow may also be tested as this may be increased at active trigger points, thus helping to isolate those in need of treatment.

Myofascial Pain Prognosis

Myofascial pain can severely affect quality of life but is not fatal. It is thought to affect people of all genders, ages, races, and socio-economic classes but is more common in those who are sedentary than those who exercise regularly and vigorously. The condition commonly presents as aching and painful muscles and joints accompanied by numbness, particularly following acute trauma such as a sudden awkward movement. Where shoulder and neck pain occurs it can make sleep uncomfortable and patients may need to use a full body pillow or other sleep aid to ensure proper rest.

Conservative Myofascial Pain Relief

Dry needling, acupuncture, or even acupressure, may be helpful for myofascial pain but patients will more often be treated with injections at trigger points of bupivacaine, etidocaine, lidocaine, saline or sterile water. Botox injections are also increasingly used for long-term pain relief in myofascial pain syndrome as they can disrupt the dysfunctional activity of motor endplates implicated in the condition. Steroids may be used in cases of inflammation and frozen shoulder. Some patients are given pain relief patches applied to trigger points for slow release of lidocaine, thus avoiding uncomfortable injections.

Treating Myofascial Pain

Physical therapy for myofascial pain involves stretching and strengthening of the muscles that appear shortened and responsible for the symptoms of the condition. Postural changes may also be made to reduce musculoskeletal triggers for the pain. Heel-lifts and other orthotics to correct leg-length discrepancies may help in pain reduction, as can massage, exercise, the use of a TENS machine, and other forms of electrical muscle stimulation (EMS).

Spinal Stenosis and Myofascial Pain Syndrome

When considering a differential diagnosis for spinal stenosis it may be that one condition is actually triggering another. A herniated disc, for example, may provide the initial stimuli for myofascial pain syndrome. Many of the medications used to treat spinal stenosis symptoms are also used in treating myofascial pain, such as NSAIDs, botox injections, and even amitriptyline (Elavil), a tricyclic antidepressant for neuropathic and chronic pain. Most patients with myofascial pain will be able to manage symptoms, given enough assistance and time, by avoiding triggers through improved ergonomics at work and home, avoiding staying one position for too long, and conducting daily range of motion exercises to facilitate muscle health. Not all back pain, radicular pain, numbness, and weakness are signs of spinal stenosis, even when an MRI shows some degree of spinal narrowing. If it’s not spinal stenosis then consider myofascial pain syndrome as catching the condition early improves the prognosis.